The present disclosure relates generally to electronic displays and more particularly, to photodetectors in a display.
This section is intended to introduce the reader to various aspects of art that may, be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Electronic devices and systems increasingly include display screens as part of the user interface of the device or system. As may be appreciated, display screens may be employed in a vide array of devices and systems including desktop computer systems, notebook computer, and handheld computing devices; well as various consumer products, such as cellular phones, televisions, and portable media players.
To display images, videos, and user interfaces, displays use arrays of pixels, each pixel having multiple colors. Primary colors of light (e.g., red, green, and blue) may be combined in each pixel to create many other colors, including white. Controllers drive pixels with coordinated instructions to create an image on the display. Some displays involve illuminating a backlight through a light-modulating liquid crystal layer (e.g., typical liquid crystal displays) while others involve directly illuminating each pixel to a desired intensity (e.g., organic light emitting diode (OLED) displays).
Because each OLED may emit its own colored light, OLED displays may be thinner and lighter than displays requiring a backlight. OLEDs may also be desirable because they may be fabricated on flexible or rigid substrates. OLED displays may also allow better viewing angles and better color than some liquid crystal displays (LCDs).
However, displays do not always operate in the same lighting environments. The perception of emitted light from a display may be affected by lighting conditions. Changing the brightness of a display can improve the perceived image of the display. For example, a dim display may provide sufficient visibility in dark environments, while a bright display may provide better visibility in a bright environment. However, controlling the brightness of a display to improve display visibility may not always be as straightforward as changing the brightness of the entire display according to a single measurement of the environmental light. For example, the ambient light on a display may not be uniform across the display, and displays are frequently moved such that their surrounding environment is dynamic.
Furthermore, the appearance of OLED displays may not remain constant indefinitely. As OLED displays age through use, their brightness and/or color may change. Some OLEDs, particularly blue OLEDs, age more quickly than others, which may change the appearance of the display. Over time as the OLEDs age, images shown on parts of the display may appear much different from the intended image. OLED controllers may make changes to compensate for such shifts in brightness and color. However, aging may occur differently across a display. For example, aging may occur in an unpredictable manner due to the manner in which end users use the device.
Further, OLED displays may be used on many mobile devices, including cellular phones and such OLED displays may also be touch-sensitive. Presently, it is desirable to utilize a proximity sensor to turn off the display when a user places the phone near the user's face. This both saves power and prevents undesired inputs to the touch screen. However, such proximity sensors are typically placed outside of the display area, thus creating some inaccuracies when turning the display on and off.